1. Field of the Invention
The present invention relates to an image processing apparatus suitably used when an image pickup apparatus such as a TV camera or battery-driven still camera has a vibration-isolating function and an object tracking function.
2. Related Background Art
Arrangements for preventing vibrations of a camera by image signal processing are described in "Frame Vibration Correcting Apparatus", Technical Report of the Association of Television, Vol. 11, No. 3, 1987 and Japanese Laid-Open Patent Application No. 61-269572. In either arrangement, a vibration angle (inclination angle) of a camera is detected, and an image is electronically or optically shifted in a direction opposite to the vibration angle of the frame by an image shift means, thereby preventing the frame vibration. In the former arrangement, the image shift means shifts a read area of an image memory in accordance with a vibration detection result. In the latter arrangement, the image shift means optimally shifts the image by a variable vertex angle prism.
The conventional arrangements, however, have a common problem. The image shift means has the limit of shift amount. When a camera angle exceeds this limit, the image vibration cannot be properly corrected, and an output image is abruptly vibrated, resulting in an uncomfortable phenomenon.